The present invention relates generally to alkylated polyalkyleneamine compounds, curing agent and amine-epoxy compositions derived from such compounds, and articles produced from such compounds and/or compositions.
Certain epoxy resins which are cured, hardened, and/or crosslinked with amine-based curing agents are well known. These amine-epoxy materials are widely used in applications ranging from coatings, adhesives, and composites, to civil engineering applications such as formulations for concrete flooring.
Due to regulations on volatile organic compounds (VOC's), it can be beneficial to reduce or eliminate emissions from organic solvents. Thus, numerous waterborne curing agent compositions and waterborne amine-epoxy compositions have been developed over the past decade. Since no organic solvent is present in some of these aqueous amine-epoxy systems, the odor, environmental, and health risks often associated with the presence of organic solvents can be eliminated.
However, many industry problems remain with waterborne curing agent and amine-epoxy systems. For instance, coatings made from aqueous amine-epoxy compositions often have poor surface appearance, characterized in the industry by the terms blush, carbamation, and exudate. These problems, in part, are due to the incompatibility of the amine curing agent and the epoxy resin, which causes phase separation and results in amine migration to the coating surface. To address this issue, it is often necessary to modify the amine curing agent to improve compatibility, which can add cost and complexity.
In certain applications, it is desirable to formulate a waterborne curing agent to relatively low solids, for example, less than 40% solids, by dilution with water. Many aqueous curing agent compositions, unfortunately, cannot be diluted without causing phase separation of the formulation, which is evidenced by cloudiness in an otherwise clear formulation. Such phase separation is undesirable as it can lead to instability of the curing agent formulation during storage. In some cases, this problem can be addressed by diluting with water at the job site and only shortly before mixing the curing agent with the epoxy resin for use. In contrast to formulating a particular solids content in a controlled manufacturing environment, job-site formulating can lead to inconsistent blends and the introduction of contaminants, which can cause performance problems in the end-use application. Another method to improve the stability of the waterborne product is to add an acid, such as a carboxylic acid. Typically, this approach adversely affects the water and chemical resistance properties of the final cured product.
Additionally, many waterborne amine-epoxy compositions have a short pot-life, sometimes as short as 30 minutes to 2 hours. Pot life is the time available to apply a coating or film to a substrate after mixing the epoxy resin and hardener or curing agent. The end of the pot-life can be evidenced by a sharp a rise in formulation viscosity, or a detrimental change in properties such as gloss or hardness of the cured coating or film. Such reduction in properties is particularly problematic, as it is not possible to detect the problem until after the coating has been applied to a substrate and cured.
It is often found that when water-based amine-epoxy systems are applied to cementitious or concrete substrates, the water-based emulsion or dispersion is destabilized. This can result in poor appearance, reduced substrate adhesion, and decreased performance properties such as chemical resistance.
There are numerous aqueous amine-based curing agent and amine-epoxy compositions that are employed in the amine-epoxy coating industry; however, none of these known products completely addresses the needs or solves the problems noted above. Accordingly, it is to this end that the present invention is directed.